Map Skins I'm completely behind. Absolutely loved Butchers Bridge.
New maps...
League of Legends maps boil down to # of lanes and # of jungles.
- 1 Lane, 0 Jungle = Howling Abyss
- 2 Lanes, 1 Jungle = Twisted Treeline
- 3 Lanes, 2 Jungles = Summoner's Rift
You're basically forced into making a 4 lane, 3 jungle map if you want something different, but even then that might not be worth it. After all, how many of us play Twisted Treeline regularly? Twisted Treeline also shows that additional objectives on the map aren't enough to make it interesting.
FPS games are allowed infinite variety in their maps because of the number of variables they can change. Heroes of the Storm was designed from the ground up for each map to be centered around neutral objectives, but League wasn't. League is designed around the lanes. You can remove neutral objectives completely and still have the same experience in League, but not so with HotS.
For those reasons, I don't think we'll ever get a new map.